1. Field of the Invention
This document relates to a vibration-sound generating device and yoke thereof and more particularly, a vibration-sound generating device and yoke thereof having improved vibration and sound performance.
2. Description of the Related Art
Recently, the release of mobile terminal, such as cellular phone or PDA, having camera and sound performance is increased rapidly. Accordingly, the needs for smaller mobile terminal is increasing, the use of vibration-sound device, which integrates a vibration motor, a receiver and a speaker so as to decrease in size and manufacturing price of the mobile terminal is augmented. Such vibration-sound devices according to the conventional art are disclosed in Korean Patent No. 10-0272305.
The vibration-sound device disclosed in KR Patent No. 10-0272305 functions by virtue of electromagnetic forces generated between a voice coil and a magnetic vibration part, which is composed of a yoke and a magnet when an alternating current is provided to the voice coil. The electromagnetic force is changed because the alternating current is provided into the voice coil. Consequently, the magnet and yoke which are supported by a suspension are vibrated by means of the electromagnetic force acted on the magnetic vibration part. Such generated vibration is transmitted to a case of the terminal through the suspension and the mobile terminal is vibrated accordingly. Besides, a diaphragm is attached on the voice coil and vibrated due to the force change of the alternating current provided into the voice coil thus, sound is generated.
The magnitude of vibration of a vibration-sound device is in proportion to the mass sum of a magnet, a yoke and a suspension that support the magnet. But the mass of the suspension and yoke of the conventional vibration-sound device is not high enough to generate desired sufficient vibration. To solve such a problem, a poise, that has more specific gravity than iron, is attached to the periphery of the yoke. But the conventional art which fabricates an extra poise and attaches it to the periphery of the yoke not only requires an additional process of attachment of the poise but also brings about a possibility of contact between the magnetic vibration part and the voice coil when the center of the poise and the yoke are eccentric.
The magnitude of sound generated by a vibration-sound device is in proportion to the intensity of a magnetic field of internal yoke in which a voice coil is positioned. But conventional vibration-sound devices have poor performance of a speaker because the magnetic flux passes through the voice coil is insufficient. This is because the volume of a magnet is limited due to the addition of the magnetic vibration part that generates vibration in compared to the usual speaker having a magnetic circuit part. Consequently, there is a necessity of magnetic field having sufficient magnetic flux density pass through the voice coil in order to improve the performance of the speaker.